Concord, New Hampshire (CNN)Under fire from Hillary Clinton and her supporters for dubbing Planned Parenthood a member of the "establishment," Bernie Sanders used the 43rd anniversary of the Roe v. Wade decision Friday to tell his supporters here he's not just fighting for income equality -- he also supports women's rights.

Speaking to students packed into the auditorium at Concord High School, the Vermont senator took on a professorial tone, laying out the creation of American democracy, but he kept circling back to the fight for women's rights.

"What Roe v. Wade was about is that women and their male allies were saying, 'You know what, on these issues, it should be with the individual, the woman, the family, the doctor, to make these decisions and not the government. That's a choice for a woman,'" Sanders said to cheers from the crowd, many of whom are not yet old enough yet to vote for him here in two weeks.

As the race has tightened in Iowa and Sanders has opened up a massive lead in New Hampshire, the Clinton campaign and its supporters have been searching for any opening on their surprisingly resilient opponent.

They found an opportunity earlier this week when Sanders lumped Planned Parenthood and the Human Rights Campaign -- two powerhouse groups on the left that recently endorsed Clinton -- in with the "establishment."

Read More

Clinton fired back almost immediately, hitting the Vermont senator on Twitter for seeming to liken the two groups to Wall Street and Washington elites.

So Sanders used the anniversary of the landmark decision to remind his supporters he's on board with women, too. The first question he took from the crowd of Concord students was about how he would support Planned Parenthood if elected president.

"I would expand funding for Planned Parenthood," he said to cheers.

The attacks have grown sharper between Clinton and Sanders in recent weeks, with Iowa and New Hampshire on the line. Whereas the two previously declined to call each other out by name, they have now dropped those pretenses.

But it's unclear how much, if any of it, is getting through to the voters.

As Cheryl Simmers and Cathy Kilday, both special education teachers at Concord High School, sat near the front of the auditorium and waited for Sanders to arrive, they pondered the most recent spat between Clinton and Sanders.

"I don't understand what's behind it all," said Simmers, 56, of Concord. "I don't know what the truth is and I don't, as a regular citizen, know how to find that information out. Is (the National Association for the Repeal of Abortion Laws), is Planned Parenthood all backed by money or is it backed by legitimately concerned individuals?"

Simmers is still deciding between Clinton and Sanders -- she likes Sanders' willingness to take on the establishment, but she wasn't pleased when he yelled over Clinton at the fourth Democratic debate earlier this week.

Kilday said she is almost 100% behind Sanders, but also said she has not completely made up her mind on both this fight and on the election.

"I'm a little torn with that because Hillary went to Wellesley (College). That's where I went to school," said Kilday, 55, who also lives in Concord. "So on a gut level, I'd like to believe that she would always be the honest go-to for women's rights rather than establishment."